Soil roasters currently used in the industry are large, cumbersome pieces of equipment which are semi-portable or permanently positioned at designated soil roasting sites. Generally, the contaminated dirt or soil at a location or contaminated site is excavated, and .the condition of the soil is tested to determine the level of contamination. The contaminated soil is then placed into containers or trucks and categorized. Finally, the dirt is transported to a designated safe soil roasting site by train or by truck.
At the safe soil roasting site, the contaminated soil is processed using a continuous flow process where soil is continuously fed into sprocket drive drums which rotate on internal axial shafts or outside bearings. Hydrocarbon contaminates are burned or vaporized from the contaminated soil in the drum, are generally passed through a baghouse or water scrubber filter to separate the hydrocarbons from dust particles, and are then passed through an afterburner to burn and eliminate the hydrocarbons. Clean air is emitted into the atmosphere through a separate exhaust stack.
Soil roasters presently available have several disadvantages. First, the contaminated soil is processed at a pre-set time and temperature. If the soil is highly contaminated or has a high moisture content, it is unlikely that the soil will be decontaminated to a desired parts per million (ppm) concentration because of the fixed time and temperature parameters. In addition, a safe soil roasting site requires more monitoring and supervision by state pollution control agency personnel to insure that all procedures are being performed correctly. Utilization of state pollution control agency personnel in this manner diverts state funds which could be utilized more productively for much needed cleanup projects. In addition, the large, stationary or semi-portable soil roasters currently being utilized consume large quantities of fuel and water to continuously process the contaminated soil. Finally, the afterburner systems which are used are separate from the stacks which emit the clean air into the atmosphere, resulting in a less efficient burning and cleaning of the air to be emitted.